Proper fan on Alternator

[lonestranger]

I am in process of converting my 64 Spyder convertible from a generator to the alternator. I gathered what I thought were the necessary parts for the conversion, which I thought was a "no brainer", as I was going to pull the necessary parts off one of the 65 140 motors I had been "storing". I had planned to follow the "forum" guide to do the conversion, including assembling the hybred alternator, using a later internal regulator alternator w/ the front housing from the 37 amp alternator, to have the necessary mounting points. That is when I notice the one piece fan/pulley on the 37 amp unit was not a reverse fan! Makes me wonder how many other 65-66 units were apparently assembled this way. I have turned this area upside down trying to locate a reversed fan for the unit, and so far the alternator shops try to tell me it won't make a difference!
They claim it will just "blow thru" the unit, as opposed to "pulling thru" the unit! Did I miss something here? I appreciate any comments, as well as question if anyone else had come across this apparent oddity?

[davemotohead]

Most times the new alternators you get from the auto parts stores have the wrong fan and you need to change them out once you buy them to the correct Corvair Fan, I have a few lying around if you want to buy one?

[66vairguy]

I am in process of converting my 64 Spyder convertible from a generator to the alternator. I gathered what I thought were the necessary parts for the conversion, which I thought was a "no brainer", as I was going to pull the necessary parts off one of the 65 140 motors I had been "storing". I had planned to follow the "forum" guide to do the conversion, including assembling the hybred alternator, using a later internal regulator alternator w/ the front housing from the 37 amp alternator, to have the necessary mounting points. That is when I notice the one piece fan/pulley on the 37 amp unit was not a reverse fan! Makes me wonder how many other 65-66 units were apparently assembled this way. I have turned this area upside down trying to locate a reversed fan for the unit, and so far the alternator shops try to tell me it won't make a difference!
They claim it will just "blow thru" the unit, as opposed to "pulling thru" the unit! Did I miss something here? I appreciate any comments, as well as question if anyone else had come across this apparent oddity?

Any shop that tells you air flow direction does not make a difference is INCOMPETENT!!! It makes a BIG difference. The regulator and power diodes are on the back of the alternator and cool air must be pulled in the back. If it is blown in from the front the air will be preheated and it also doesn't distribute properly over the components causing overheated components. I see the wrong fans on Corvair alternators and due to the fact most Corvairs don't demand much electrical power it works - for a while.

Also note that unlike the old generators - the fan nut on the Corvair alternator is not reverse threaded for the counter clockwise rotation. You must use a new lock washer and tighten the nut sufficiently.

[lonestranger]

I thank the members for their reply to my inquiry. After running all over town looking for a proper "reverse flow" fan for my conversion (to no avail I might add!) In desperation, it occurred to me that the only reverse fan I had seen was the one on my generator - upon test fitting it to my " new" hybrid alternator, I found that with a little juggling of spacers, it fit fine. Problem solved - just for the information of the forum. Now all I have to do is the modification to the wiring harness to eliminate the external regulator, and I can proceed with the next item on my list!

[davemotohead]

You put a Gen fan on a Alternator? Do you have a picture?

[lonestranger]

You put a Gen fan on a Alternator? Do you have a picture?

I will attempt to get a picture of it and post it. It is the one piece fan-pulley that was on my 64 spyder engine. I used the internal spacer (approx. 1/2 in) from the "new" internal reg alternator behind the 37 amp "end housing" (the one with corvair mounting holes), and the small spacer (approx. 1/16 thick) that was originally behind the generator fan unit, behind the fan assembly. It then bolted up and is spaced as original. Other than that, it goes together with no problem. The original keyway is not used, as the later alternator does not have the provision for a key, and does not use one on its intended application. As I said, I will attempt to take picture and post, however I am not the swiftest when it comes to computer "activity".

[davemotohead]

I am thinking you need to get the correct fan/pulley set up, the 64 fan has a shield on it and is completely different than the correct alternator pulley fan.

[lonestranger]

I am thinking you need to get the correct fan/pulley set up, the 64 fan has a shield on it and is completely different than the correct alternator pulley fan.

Yes, the 64 fan has a shield on it, however it is on the "pulley side" of the fan, rather than being on the alternator side, as most conventional fans are constructed. Therefore it acts as needed, for pulling air through the alternator, when spun in the reverse as it is on the Corvair. I will try to take my hybred alternator back apart and take pictures of the parts. Then all I have to do is download them to my computer and endeavor to post them on the forum! Hope my explanation make sense, in case I am not successful with photo posting.

Note: My main concern is that, upon looking at the late alternator "rear housing" I find it does not have much in the way of openings, when compared to the 37 amp corvair alternator. The primary opening appears to be for ventilation for the diode heat sink. apparently that is enough ventilation for the unit. We shall see!
also:

Note: a final correction as to the dimensions of the two spacers, now that the alternator is apart again: The internal spacer (which apparently sets end play) is 3/8" and the spacer behind the fan/pulley is 3/16". The internal spacer is what came inside the new internal reg alternator and the spacer behind the fan/pulley was originally behind the fan/pulley on the 37 amp Alternator. This fan/pulley was not the proper reverse rotation fan, which started this whole saga!!